Vol. 54.] DIVISIONS OF SO-CALLED * JURASSIC ' TIME. 



461 



Family POLYMORPHID^. 



Genus. 

 Catulloceras. 

 Cycloceras. 

 Dumortieria. 



Tmetoceras. 



Tropidoceras. 



Uptonia. 



Family PSILOCERATIDJS. 



Genus. 

 Caloceyas. 

 Psiloceras. 

 Schlotheimia. 

 Tmcegoceras. 

 WcBhneroceras. 



Species. 

 Bumortieri, Leeshergi. 

 Valdani, Maugenesti. 

 Levesquei, radians, 

 grammoceratoides-gvonp. 

 scissttm. 

 Masseanum. 

 Jamesoni, Beynardi. 



Species. 

 torus, Johnstoni, liassicum. 

 planorbis. 



angulata, marmorea. 

 latesulcatum. 

 tenerum, megastoma. 



Family — ? Eadical Stoct. 



Genus. Species. 



Cymbites. globosiis. 



Hudlestonia} affinis, Sinon, 



Paroniceras. sternale. 



Family STEPHEOOERATID^. 



Genus. 



Coeloceras. 



CoUina. 



Dactylioceras. 



Emileia. 



Macrocephalites. 

 Morphoceras. 



Parkinsonia. 



Perisphinctes. 



Peronoceras. 



Sphcsroceras. 

 Stepheoceras. 



Species. 

 pettus, Blagdeni, 

 gemma. 



commune, annulatum. 

 Bavidsoni-gvoup. 

 Brocchi, polymera. 

 Garaiitianum-group. 

 linguiferum-grou'p. 

 macrocephalus. 

 pseicdoanceps, dimorphum. 

 niortensis-grouip. 

 Parkinsoni. 

 Martinsii. 

 fihulatum. 

 Sauzei-gYonp. 

 Gervillii, Brongniarti. 

 Humphriesianum . 

 zigzag-gvonp. 



The inclusion of a generic name does not imply the expression of 

 any opinion as to its validity or otherwise. Nor does the mention of an 

 ammonite-group imply that it is entitled necessarily to generic rank. 



Quenstedt's Psilonoticeras, Arieticeras, etc., are really invalid, 

 because they were admittedly proposed as mere modifications of 

 existing names — of Psiloceras and Arietites respectively. 



Munier-Chalmas's Oadomites and Mormannites, of the family 

 Stepheoceratidae, were names given for supposed sexual features. 



^ The affinities of Hudlestonia must be considered very doubtful. It is 

 possibly an extreme development of the radical stock. There is another similar 

 series — the staufensis-group, its horizon given as Murchisoncs zone, its date per- 

 haps scissi or Murchisoncs hemera — which may be another extreme development. 



